Iron-nickel alloy



Patented May 27, 1930 UNITED STATES PATENT OFFICE FRITZ STKBLEIN, OF ESSEN, GERMANY, ASSIGNOR TO FRIED. KRUPP AKTIENGESELL- SCHAFT, 0F ESSEN-ON-THE-RUHR, GERMANY IRON-NICKEL ALLOY No Drawing. Application filed October 31, 1928, Serial No. 316,356, and in Germany December 24, 1927.

Nickel-iron alloys that contain about 50 to 85 per cent of nickel and more particularly those containing 78.5 per cent of nickel, possess a high initial permeability, that means the proportion B:H of these alloys has a value, even with quite small field strengths, which is a multiple of the corresponding value of quite soft iron sorts. An undesired property of these alloys, however, consists in the fact that in order to acquire their highest initial permeability the must be subjected to rather a complicate heat treatment. With the above-indicated nickel-iron alloy containing 78.5 per cent of nickel the heat treatment required consists e. g. in heating the alloyto 900 degrees C. and cooling it first slowly to 600 degrees C. and then as quickly as possible to room temperature. \Vith a nickel-iron alloy, however, that contains about 50 per cent of nickel, the best heat treatment consists in glowing it a comparatively long time at about 1100 degrees C. and thereupon cooling it slowly.

A further unfavourable property of the indicated nickel-iron alloys is their small specific resistance which with the nickel-iron alloy containing 50 ()per cent of nickel amounts to about 0.47 Ohm. mm /m and with that containing 78.5 per cent of nickel to about 0.22 Ohm. min /m and results in high eddy-current losses and their consequences (diii'erently great decrease of the apparent permeability with different alternatlng current frequencies, and distortions resulting therefrom).

Now the subject-matter of the invention is an alloy which besides iron contains about 33 to 48 per cent of nickel and 0.3 to 3 per cent of silicon, the invention further consisting in employing these alloys and alloys known per se which besides iron contain about 33 to 48 per cent of nickel and 0.3 to 5 per cent of sili- 11000 lines of force in each cm which is about equal to the saturation intensity of the nickel-iron alloy which contains 78.5 per cent of nickel.

The fact that the percentage of nickel is considerably lower in the alloys indicated above than in the known nickel-iron alloys which possess high initial permeability affords the further advanta e of the former being much cheaper than tie latter, despite their good electric and magnetic properties. Furthermore, the fact that the good electric and magnetic properties were obtained despite the low ercentage of nickel proves that a deciding infiuence has to be attached to the addition of silicon. Tests made with two iron-nickel alloys each containing 40 per cent of nickel but one of which contained 2 per cent of silicon while the other did not contain silicon, proved that the silicon-iron-nickel alloy possesses an initial permeability of an average increase of 1000 units.

The impurities entering the alloys in the producing process are of no consequence in practice.

V hat I claim and desire to secure by Letters Patent, is

i 1. An iron-nickel alloy containing about 33 to 48 per cent of nickel, 0.3 to 3 per cent of silicon, and the remainder iron.

2. Articles of high initial permeability consisting of about 33 to 48 percent of nickel, 0.3 to 5 per cent of silicon, and the remainder lIOIl.

3. A magnetic material which comprises as an essential component a composition containing 33 to 48% of nickel, 0.3 to 5% of FRITZ sTiiBLEIN. 

